Sealed cooling system for an internal combustion engine



March 8, 1966 N B. H. SIMPSON 3,238,932

SEALED COOLING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Filed March 30,1964 BRUCE bfJ/MPJO/V INVENTOR A R/VE'YS United States Patent Office3,238,932 Patented Mar. 8, 1966 3,238,932 SEALED COOLING SYSTEM FOR ANINTERNAL COMBUSTIQN ENGINE Bruce H. Simpson, Deal-born, Mich., assignorto Ford Motor Company, Dearborn, Micl1., a corporation of Delaware FiledMar. 30, 1964, Ser. No. 355,727 2 Claims. (Cl. 123-415) This inventionrelates to a sealed cooling system for an internal combustion engine andmore particularly to the sealed cooling system that embodies a novelmanner of precluding air contact with the coolant.

The emphasis upon reduced maintenance motor vehicles has created ademand for sealed engine cooling systems. In liquid cooled internalcombustion engines, the coolant of a sealed system should containsufficient inhibitors to preclude the formation of rust. The coolantalso should have a low freezing point to meet all climatic conditions.It is additionally desirable to provide a coolant having a high boilingpoint to permit higher engine operating temperatures and to reduce thepossibility of coolant losses through boiling.

Although long-life coolants have been proposed that retain their rustinhibiting and low freezing point characteristics, these coolan-ts candeteriorate within the normal vehicle life. One major cause of coolantdeterioration is the chemical action that results from the contact ofthe coolant at high engine operating temperatures with air. It isdesirable, therefore, to purge the cooling system of air to extend thelife of the coolant.

The volume of the liquid coolant varies greatly between the lowestanticipated ambient temperature and the normal engine operatingtemperature. Some form of expansion device must be provided toaccommodate these variations in coolant volume. In the conventionaldownflow radiator, the upper header tank serves as an expansion device.In a cross flow radiator, a separate expansion tank must be employed.

The header tank of a downflow radiator or the expansion tank of a crossflow radiator have sufficient air space to permit coolant expansion. Theliquid turbulence within the expansion device, however, causes the airto enter the cooling system. Thus, even though the system may have beenoriginally purged of air, air will soon enter the system and causedeterioration of the coolant.

It, therefore, is the principle object of this invention to provide asealed cooling system that precludes the contact of air with the liquidcoolant.

A sealed liquid cooling system for an internal combustion engineembodying this invention comprises a cooling jacket for the engine. Aheat exchanger is provided to dissipate the heat generated by theengine. Means are provided for circulating liquid coolant between theheat exchanger and the engine cooling jacket. An expansion device isprovided to accommodate temperature induced variations in the volume ofthe liquid coolant. The expansion device comprises a substantially rigidcontainer having an impervious flexible wall. The flexible wall is incontact with the liquid coolant at the minimum expected coolant volumewithin the system and is decformable by the coolant upon temperatureinduced increases in coolant volume.

Further objects and advantages of this invention will become moreapparent when considered in conjunction with the accompanying drawings,wherein:

FIGURE 1 is a schematic view of an internal combustion engine and itscooling system showing a first embodiment of the invention.

FIGURE 2 is a partial cross sectional view of a radiator for an internalcombustion engine showing another embodiment of the invention.

Referring now in detail to the drawings and in particular to FIGURE 1, aliquid cooled internal combustion engine is identified generally by thereference numeral 11. The engine 11 includes a cylinder block -12 and acylinder head 13 that are provided with cooling jackets through which asuitable liquid coolant may be circulated. A crankshaft driven coolantpump 14 is positioned at the front of the cylinder block 12 forcirculating the liquid coolant.

A cross-flow radiator or heat exchanger, indicated generally by thereference numeral 15, is positioned at the front of the engine 11. Theradiator 15 has a central section 16 made up of a plurality of coolantflow tubes and heat exchanging fins. Header tanks 17 and 18 arepositioned at each end of the section =16 in open communication with thetubes. An engine driven fan 19 causes air circulation across theradiator central section 16 to dissipate the heat generated by engineoperation.

A coolant outlet fitting 2 1 is positioned at the front of the cylinderhead 13. A coolant inlet fitting 22 is positioned at the upper end ofthe header tank 17. A flexible hose 23 is connected at opposite ends tothe fittings 2'1 and 22 as by the clamps 24 and 25 for coolant flow fromthe engine cooling jacket to the radiator 15. A coolant outlet fitting26 is positioned at the bottom of the header tank 18. A flexible hose 27interconnects the outlet fitting 26 with the inlet side of the coolantpump 14.

The coolant within the engine 11, hoses 23 and 27, and the radiator 15is purged of air when the system is initially filled. The aforementionedelements are filled completely with coolant at a normal ambienttemperature. The coolant will expand at engine operating temperatureshowever. An expansion device, indicated generally by the referencenumeral 28, is provided to accommodate the variations in volume of theengine coolant. The expansion device 28 is the highest point in thesystem and comprises a substantially rigid tank 29 having a coolantfitting 31. A flexible hose 3-2 is connected at one end to the fitting31 by a clamp 33. The other end of the hose 3-2 is connected to acoolant fitting 34 positioned at the upper end of the header tank 17 bya clamp 35.

A flexible wall 36 extends across the tank 29 on one side of the fitting31. The cooling system is charged with sufficient coolant so that thecoolant will contact the flexible wall 36 in an unexpanded state, asdenoted by the line 3611, at the lowest anticipated ambient temperature.As the coolant within the system becomes heated by engine operation orwith increases in ambient temperature, the coolant will expand and causethe flexible Wall 36 to deform. It should be readily apparent that atall engine temperatures the impervious flexible well 36 will precludeentry of air into the cooling system although expansions in coolantvolume are accommodated.

The internal volume of the tank 29 is chosen to limit the deformation ofthe flexible wall 36 as shown by the broken line 36b in the drawing. Itis desirable to pressurize the cooling system to increase the boilingpoint of the coolant. This may be done by selecting a proper internalvolume of the tank 29 to achieve the desired pressurization.

A pressure relief valve, indicated generally by the reference numeral 37may be provided in the tank 29 on the coolant side of the flexible wall36. The pressure relief valve may be threaded onto a fitting 38 in thetank 29 to permit removal and charging of the system. The pressurerelief valve 37 includes a movable valve member 39 that is biased by acoil spring 41 to a closed position. The spring tension is chosen sothat the valve member 39 will be unseated when the coolant pressureexceeds a predetermined value. During most normal stages of engineoperation the valve member 39 will be closed.

The previously described embodiment employed a cross flow radiator andrequired a separate expansion device. If a downflow radiator isprovided, it is possible to combine the expansion device with the upperradiator header tank. Such an embodiment is shown in FIGURE 2. Theengine and the lower portion of the radiator have not been shown sincethese features are conventional. It is to be understood that the engineand its coolant inlet and outlets may be the same as shown in FIGURE 1.The engine coolant inlet may be connected to the lower header tank ofthe radiator by a flexible hose as is well known.

Referring now specifically to FIGURE 2 a downflow radiator is indicatedgenerally by the reference numeral 51. The radiator 51 includes aplurality of flow tubes 52 surrounded by heat exchanging fins 53. Anupper header tank 54 is secured to the radiator in open communication atits lower side with the flow tubes 52. A coolant inlet fitting 55 of theradiator 51 receives liquid coolant through a flexible hose 56 that isin communication with the engine (not shown). A clamp 57 provides aliquid tight seal between the hose 56 and the inlet fitting 55.

A flexible, impervious wall 58 extends across the header tank 54. As inthe previously described embodiment, the liquid in the radiator 51, theengine and the coolant hoses has been purged of air when the system wasinitially filled. The flexible wall 58 is in contact with the coolantcompletely across the header tank 54 at the lowest anticipated ambienttemperature. The inlet fitting S lies below the wall 58 at thistemperature.

As the engine coolant temperature rises, the increase in volume of thecoolant deforms the flexible wall 58. The internal volume of the headertank 54 is sufficient to accommodate the increase in volume at theengine normal operating temperature. In this condition the flexible wall58 is deformed into contact with the upper surface of the header tank 54as denoted by dotted lines in FIGURE 2. If desired the system may bepressurized through a reduction in the volume of the header tank 54.

Means are provided to permit charging of the coolant in the system andto provide for pressure relief. These means comprise a fitting 59 thatextends from above the upper surface of the header tank 54 into theheader tank below the flexible wall 58. A combined filler cap andpressure relief valve 61, which may be of the type shown in FIGURE 1, ispositioned at the inlet of the fitting 59.

It is to be understood that various changes and modifications may bemade without departing from the spirit and scope of the invention, asdefined by the appended claims.

I claim:

1. A sealed liquid cooling system for an internal combustion enginecomprising a cooling jacket for said engine, a heat exchanger, said heatexchanger comprising a plurality of coolant flow passages interconnectedby at least one header tank, means for circulating liquid coolantbetween said heat exchanger and said cooling jacket, the liquid coolantcontained in said cooling jacket, said coolant flow passages and saidlast-named means being substantially purged of air, and a flexible wallextending across said header tank, said flexible wall being in contactwith the liquid coolant at the minimum expected coolant volume withinsaid system and being impervious for precluding entry of air into saidsystem, said flexible wall being deformable upon temperature inducedincreases in the coolant volume.

2. A sealed liquid cooling system as defined by claim 1 wherein theinternal volume of the header tank is equal to no more than the increasein volume of the liquid coolant experienced by heating the coolant fromthe lowest anticipated ambient temperature to normal cooling systemoperating temperatures.

References Cited by the Examiner UNITED STATES PATENTS 2,147,699 2/1939Hardiman --34 3,076,479 2/1963 Ottung 12341.5 X

3,168,080 2/1965 Latterner 123-4126 FOREIGN PATENTS 964,429 7/1964 GreatBritain.

KARL J. ALBRECHT Primary Examiner.

MARK NEWMAN, Examiner.

1. A SEALED LIQUID COOLING SYSTEM FOR AN INTERNAL COMBUSTION ENGINECOMPRISING A COOLING JACKET FOR SAID ENGINE, A HEAT EXCHANGER, SAID HEATEXCHANGER COMPRISING A PLURALITY OF COOLANT FLOW PASSAGES INTERCONNECTEDBY AT LEAST ONE HEADER TANK, MEANS FOR CIRCULATING LIQUID COOLANTBETWEEN SAID HEAT EXCHANGER AND SAID COOLING JACKET, THE LIQUID COOLANTCONTAINED IN SAID COOLING JACKET, SAID COOLANT FLOW PASSAGES AND SAIDLAST-NAMED MEANS BEING SUBSTANTIALLY PURGED OF AIR, AND A FLEXIBLE WALLEXTENDING ACROSS SAID HEADER TANK, SAID FLEXIBLE WALL BEING IN CONTACTWITH THE LIQUID COOLANT AT THE MINIMUM EXPECTED COOLANT VOLUME WITHINSAID SYSTEM SAID BEING IMPERVIOUS FOR PRECLUDING ENTRY OF AIR INTO SAIDSYSTEM, SAID FLEXIBLE WALL BEING DEFORMABLE UPON TEMPERATURE INDUCEDINCREASES IN THE COOLANT VOLUME.